OFFSET
0,2
COMMENTS
Position of zeros in A025667. - R. J. Mathar, Jul 06 2025
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 0..10000
FORMULA
From Amiram Eldar, Nov 13 2025: (Start)
A003595(a(n)) = 5^n.
a(n) = 1 + Sum_{k=0..n} ceiling(k * c), where c = log_7(5) (A153203).
a(n) ~ c * n^2 / 2, where c is defined above. (End)
MATHEMATICA
Accumulate[Table[Ceiling[n * Log[7, 5]], {n, 0, 60}]] + 1 (* Amiram Eldar, Nov 13 2025 *)
PROG
(PARI) a(n)=my(N=1); n+1+sum(i=1, n, logint(N*=5, 7)); \\ Charles R Greathouse IV, Jan 11 2018
(PARI) first(n)=my(s, N=1/5); vector(n+1, i, s+=logint(N*=5, 7)+1) \\ Charles R Greathouse IV, Jan 11 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Offset corrected by Charles R Greathouse IV, Jan 11 2018
STATUS
approved